Canis ISSN: 2398-2942

Allergy testing

Contributor(s): David Godfrey, David Scarff

Overview

  • Detection of allergen specific IgE antibodies in blood sample may indicate hypersensitivity to airborne allergens.
  • This is a direct alternative to intradermal allergy testing Skin: intradermal test.
  • Either method will enable the identification of allergens responsible for the allergy and the production of a desensitizing immunotherapy Allergen-specific immunotherapy or, in some cases, elimination of the allergens from animal's environment.
  • There is no proof of the validity of serological testing to diagnose or rule out clinical signs due to an adverse reactions to food/food allergy Skin: food hypersensitivity Food allergy testing.

Sampling

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Tests

Methodologies

  • ELISA test Enzyme linked immunosorbent assay (ELISA) for allergen-specific IgE. In most labs this is based on a monoclonal antibody. Different technologies are available but there is no clear scientific evidence that proves one is better than others.

Validity

Sensitivity

  • Probably as sensitive as intradermal skin testing for selecting allergens for hyposensitization.

Specificity

  • False positives are common - depending on the cut-off used for a positive result.
  • Poor specificity (possibly less than intradermal skin test).

Predictive value

  • In theory a negative IgE serum titer effectively excludes hypersensitivity to that allergen.
  • A positive test does not prove the clinical importance of that allergen to this patient. The best evidence is a subsequent clinical improvement after immunotherapy using that allergen.
  • Serology is probably as sensitive as intradermal skin testing for selecting allergens for hyposensitization.

Technique (intrinsic) limitations

  • Results may not accurately predict the allergens causing clinical signs.
  • Significant antibody may be confined to mucosal surface and not present in serum.
  • If multiple allergens are tested against the sera the test is less specific. "Screening tests" will generate more false negative results than individual allergen tests and their use is purely a financial compromise.
  • Individual testing is the most sensitive and specific.

Technician (extrinsic) limitations

  • A standard assay would include a panel of all the major pollens, mite and mold spore allergens in the area.
  • Whole flea or (much better) flea saliva antigen may often be included. This is a test for flea bite hypersensitivity Skin: flea bite hypersensitivity rather than atopic dermatitis.
  • There are a number of different panels to choose from so it is important to select one from the relevant geographical area.

Result Data

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Further Reading

Publications

Refereed papers

  • Recent references from VetMedResource and PubMed.
  • Favrot C, Steffan J, Seewald W & Picco F (2010) A prospective study on the clinical features of chronic canine atopic dermatitis and its diagnosis. Vet Dermatol 21(1), 23-31 PubMed.
  • Olivry T , International Task Force of Canine Atopic Dermatitis (2010) New diagnostic crtieria for canine atopic dermatitis. Vet Dermatol 21(1), 124-127 PubMed.
  • Mueller R S, Burrows A & Tsohalis J (1999) Comparison of intradermal testing and serum testing for allergen-specific IgE using monoclonal IgE antibodies in 84 atopic dogs. Aust Vet J 77, 290-294.
  • Bond R, Thorogood S C & Lloyd D H (1994) Evaluation of two enzyme-linked immunosorbent assays for the diagnosis of canine atopy [see comments] Vet Rec 135, 130-133.
  • Miller W H Jr et al (1993) Evaluation of the performance of a neurologic allergy system in atopic dogs. JAAHA 29, 545.
  • Codner E C & Lessard P (1993) Comparison of intradermal allergy test and ELISA in dogs with allergic skin disease. JAVMA 202, 739-743.
  • Halliwell R E, Kunkle G A (1978) The radioallergosorbent test in the diagnosis of canine atopic disease. J Allergy Clin Immunol 62, 236-242.


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